The purpose of this quantitative correlational research was to investigate the relationship between global oxygen delivery at or above the critical level (DO2crit) of 272mL · min-1 · m-2 and the preservation of neurocognitive function in adult patients who presented for aortic surgery utilizing cardiopulmonary bypass (CPB), at a large hospital in the midwest United States in 2012-2014. The study was based on Ranucci’s findings that DO2crit for aerobic metabolism reduces the incidence of post-operative acute kidney injury. The research was conducted on archival data from a sample of 100 CPB patients aged 50 or older. The average values of oxygen delivery were used to classify patients into those for whom the delivery met the DO2crit and those for whom it did not meet the DO2crit. The validated instruments used to measure cognitive function pre- and post-op were the Cerebral Performance Category and the modified Rankin Scale. The pre-op to post-op differences were used to classify the patients as having suffered significant cognitive loss or not. Data from both yielded identical classifications, indicating concurrent validity. The result of the chi-square analysis did not reach statistical significance, X2 (1, 100) = 3.27, p = .07. The descriptive statistics for a subsample that excluded death and stroke cases showed that the proportion of “significant loss” to “no significant loss” was 1.72% in the group where the DO2crit was met, compared to 24% in the group where the DO2crit was not met. These findings justify further research with controls and a larger sample.